Discrepancy between in vitro and in vivo assays for the susceptibility of Bacillus C.I.P. 5832 to antimicrobial agents.
In vitro, avoparcin, flavomycin, virginiamycin bacitracin, trimethoprim + sulfadimethoxine, colistin, spiramycin, oxolinic acid, lincomycin + spectinomycin and a mixture of organic acids were able to inhibit Bacillus C.I.P. 5832. In vivo, none of these antibacterial agents, at the levels incorporated in feeds, could affect the viable bacillus count in the caecal content of chickens. In another in vitro assay, olaquindox, carbadox and tylosin were also effective in inhibiting Bacillus C.I.P. 5832. But, concomitantly administered with carbadox or tylosin, Bacillus C.I.P. 5832 still promoted growth and feed conversion of fattening pigs. These results, as well as data of the quoted literature, suggest that the current in vitro techniques should not be used to screen the susceptibility of Bacillus C.I.P. 5832 to antimicrobial agents. Only in vivo assays seem to be of value.
Tirel
M L
ML
Faculté des Sciences et Techniques, Laboratoire de Microbiologie Appliquée, Brest, France.
Levesque
A
A
Lefrancois
S
S
Ridremont
B
B
Nguyen
T H
TH
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001407:Bacillus / Q000187:drug effects*; D001424:Bacterial Infections / Q000188:drug therapy*; D002432:Cecum / Q000382:microbiology; D002645:Chickens; D015169:Colony Count, Microbial; D005260:Female; D008297:Male; D013552:Swine / Q000254:growth & development
D000900:Anti-Bacterial Agents